The word “bipod” is derived from the Latin and Greek roots “bi” and “pod” meaning “two” and “foot” respectively. Bipods may be used to stabilize a variety of devices that require steadying during use, such as, for example, weapons, photographic equipment, and videographic equipment.
A bipod may be used as an attachment for a firearm to provide stability and a steady plane while aiming and shooting. The created stability is intended to help steady the firearm during “gun laying” or aiming in order to ensure and increase accuracy. Gun laying involves moving the axis of the bore of the barrel in two planes, namely the horizontal and vertical planes. A gun is traversed—rotated in a horizontal plane—to align it with the target, and elevated—moved in the vertical plane—to range it to the target. The bipod provides significant stability along the two axes of motion.
The basic concept of a bipod dates back to pre-20th century times. The Harris bipod, an early example of which may be found in U.S. Pat. No. 3,327,422 to Harris, quickly became an industry standard. The Harris bipod includes a mount attached to the underside of the fore-end of the stock of the firearm using a threaded swivel as a fastener. A clamp grips both sides of the swivel with pins that lock into the holes of the swivel. Tightening a screw on the clamp causes it to be pulled downward and forces it to squeeze on the swivel through a hole to prevent the pins from dislodging. The mount then has two legs that are attached on pivot points with springs attached along the leg and back to the mount. This allows the legs to be pivoted downward past a point where the spring pulls the legs into a position with resistance to keep them from folding up; however, the legs do not lock. The legs in the folded up position run parallel to the barrel in order minimize the profile and therefore minimize snagging on objects along the way when moving the firearm from one shooting position or location to another. In addition, this makes storing the firearm easier with the bipod attached.
Continuing with the Harris bipod, the legs are formed as tubes within tubes that allow the legs to be extended. The leg extensions have grooves cut in them to extend the legs in discreet increments to raise the height. A spring-loaded mechanism locks into the grooves. This allows some variation in setting the height of the bipod to accommodate the shooter's preference to accommodate his or her anatomy for a more comfortable position to make a shot. The legs are spring-loaded to retract to quickly stow the legs for movement. Stowing the legs involves pushing the legs forward past the spring's point of resistance where the spring begins to pull the legs upward. The legs have feet or caps on their ends made of rubber that when set on a surface provide a grip and added stability in order to steady the firearm for a shot. Leapers, Inc. manufactures the UTG Bipod with similar features as the Harris bi pod.
Another popular bipod, manufactured by B&T Industries, LLC, is the Atlas bipod, an example of which may be found in U.S. Pat. No. 7,614,174 to Beltz. This particular design utilizes a “QD” or quick disconnect and connect mechanism to secure to a rail mounted to the underside of the fore-end of a stock on a firearm. The legs of this design can be angled forward at preselected angles based on a pin mechanism that uses a spring-loaded button that interfaces with a corresponding cog on the base of the bipod. The design also has leg extensions to adjust the height of the bipod. The leg extensions utilize a spring-loaded collar that is pulled downward along the axis of the leg to release and pull the leg extensions into position. The legs have corresponding notches to lock into various settings for adjustment. This allows the legs to be extended in a telescopic fashion to a desired level. This bipod is also available with modular extensions that can be installed to increase the height and reattach the feet using an Allen key. A variety of feet are also available. The Atlas bipod also allows the mount to swivel so the firearm can be panned left to right for moving targets. In addition, the firearm can also be canted since the mount can swivel on an axis parallel to the barrel. Actuation of the legs may be performed using one hand, but it is very difficult to do while the firearm is shouldered since the shooter has to reach far forward unless the bipod is mounted backwards on the mount.
GG&G manufactures the XDS bipod, which includes features of both the Harris bipod and the Atlas bipod. It also utilizes a QD mechanism to connect to a rail. The legs extend through a threaded knob that when turned releases the legs to telescopically extend the legs. The legs are rotated down into position and can be locked via a mechanism of a lever that is spring loaded. Depressing the lever releases the lock so the legs can be folded up and stowed for movement. The legs of this design can also be angled forward like the Atlas bipod; however, there is only one setting at 45 degrees.
Versa-Pod manufactures a variety of bipods including the 150 Series of bipods, an example of which being the 150-052 bipod. This bipod requires a special adapter to be placed on the firearm for mounting which may be attached in turn to a standard Picatinny rail. The design utilizes a ball joint to rotate or angle the firearm. This ball joint allows for panning the firearm during tracking while a screw is provided that can be tightened to eliminate movement as desired. The legs of this design are spring loaded in a direction of extension rather than retraction. The design has a unique mechanism in which the leg, when in the folded up position, fold together forward; however when pulled down, the legs spread apart with a spring between the legs. The legs can also be folded backward. There is no positive lock on the legs.
The Mako Group manufactures a line of bipods known as the “Vertical Foregrip” w/Integrated Adjustable Quick Release bipod, examples of which may be found in U.S. Pat. Nos. 7,823,855 and 7,909,301 to Faifer, that double-functions as a single handle/forward grip that opens and converts into a bipod. A single hand can be used to deploy the bipod; however, the handle or forward grip itself cannot be folded up and stowed during movement. Some versions include an integrated flashlight mount. The design utilizes a unique slide mechanism in which a button is depressed to move it and open the feature to slide onto a rail system. Once it reaches a desired position along the rail, the shooter releases the button to allow the slide to move into a position in which a locking lug slides into one of the slots on the Picatinny rail.
With the exception of the Mako Group bipod, current designs all require the shooter or shooter in many cases to bring the firearm off the shoulder in order to use the hand that typically grips the stock or pistol grip to actuate the legs into a downward position by hand to set up for a shot. This may be critical time in which the shooter needs to setup, deploy and, steady the firearm, and acquire the target through sights or optics in order to make a shot. At this point, the target may have moved and gone to a place of cover or concealment.
Another issue with many of the current designs is the complex actuation mechanisms that must be grasped and positioned to release and extend the legs to change the set elevation. Changing the set elevation is important to bring the firearm to a comfortable position in relation to the anatomy of the shooter. In many cases, the levers are not ergonomically designed or positioned for easy actuation compatible with the anatomy of the fingers and hands. The levers have to be held while the firearm is lifted for the legs to be extended or the firearm is lifted to let the legs adjust and then locked down. A few of the bipods leg extensions are spring loaded so that when actuated extends the legs out to the furthest adjustment or they retract fully. As a result, the firearm has to be gripped and held, taking it off the shoulder until the legs can be locked.
To lock the legs, many of the current designs use extension springs that provide a positive force pulling the main legs down into position once the legs are rotated past a point where the spring acts in this downward direction. This requires the use of both hands: one hand holds the firearm while the other hand grips the leg and pulls it downward against the resisting spring past the point of resistance. This has to be repeated on the other side for the bipods where the main legs act independent of one another. Again, the firearm has to be taken off the shoulder to deploy.
The pads or feet of many of the designs use one of two types. One seems to be a rubber foot that is round but has angled or chamfered surfaces that actually interface with the ground once the legs are deployed into position. The other is a flat plate at the end of the leg that interfaces with the ground in a normal orientation once the legs are deployed. The former round rubber foot when contacted with the ground only provides one line of contact. The flat plated feet provide a surface but once the bipod is slightly tilted, which is done in most cases, still only provides one line of contact.